9704651 Mojzsis2 The P.I. will examine a sample of the aqueous alteration lithologies of the ALH 84001 meteorite (McKay et al., 1996) and determine the phosphate mineralogy and inclusion compositions contained within it. The other martian meteorite containing obvious aqueous mineral assemblages, the EET79001 meteorite (Gooding et al., 1988), was affected by chemically active aqueous solutions. Geological evidence derived from remotely sensed data pointing to abundant liquid water in the past on Mars include large-scale remnant hydrologic features such as outflow channels, valley networks, drainage systems, lake deposits, possible ancient seas, and even glaciated terrain. Carbonates and other salts could have precipitated out of water at the surface in equilibrium with an ancient atmosphere on Mars before climatic conditions fell below the stability field of liquid water. Low temperature mineral assemblages contain direct information about their medium of precipitation, and aqueous mineral formation may have contained at depth or in a hydrothermal regime on Mars until heat from volcanism ceased; the pressure and temperature conditions would tend in these cases to satisfy the stability of liquid water.
